1. Field of the Invention
The present invention relates to an image forming optical system and an electronic image pickup apparatus using the same.
2. Description of the Related Arts
A digital camera has reached a level of being used practically, regarding making large the number of pixels (high image quality), and small-sizing and slimming. Also from a function point of view and a market point of view, a digital camera has substituted a silver salt 35 mm film camera. Therefore, as a next trend of evolution, an improvement in optical specifications, such as a high zooming ratio, and a wide angle, as well as, further increase in the number of pixels with the same size and slimness, have been sought strongly.
For improving specifications such as the zooming ratio and an angle of field with the same slimness of a digital camera, it is necessary to go on improving these specifications while maintaining same overall optical length of a zoom lens. As a conventional zoom lens having a short overall length, which is suitable for slimming of a main body of a digital camera, a zoom lens described in Japanese Patent Application Laid-open Publication No. 2003-140043 is available.